Voltage Stabilizer
Disclosed herein is a fast voltage stabilizer wherein an actual voltage across a targeted electronic element is sensed. The actual voltage is compared with a reference voltage. A control signal is generated, wherein in response to the control signal, an external current path is provided to maintain current flow and stabilize the actual voltage through charging or discharging an input capacitor and a supply filtering capacitor. Under an arbitrary supply voltage variation, a fast dynamic response to regulate the voltage across the targeted electronic element is provided no matter what the operating mode of the entire electrical circuit is, including but not limited by constant current mode, constant output resistant mode and constant power mode.
This disclosure relates to a voltage stabilizer and, more particularly, to a fast voltage stabilizer configured to minimize voltage fluctuation.
A flyback power factor corrector (PFC) has been widely used in low-power applications. Its basic structure consists of a diode bridge for initial ac-dc rectification and a flyback dc-dc converter for shaping the waveform of the input current in phase with the supply voltage. As the input current of the flyback dc-dc converter is pulsating, an input filter is required to prevent the unwanted pulsating current from getting into the ac supply. Many research efforts have been emphasized on the structure, modeling, and design optimization of the input filter (for example, see “C. Tung et al., “Flyback PFC With a Series-Pass Module in Cascode Structure for Input Current Shaping” in IEEE Transactions on Power Electronics, vol. 34, no. 6, pp. 5362-5377, June 2019 [“Tung”]” [the entirety of which is herein incorporated by reference]).
The input filter in a power electronic system is used to prevent unwanted switching harmonics, radiated or conducted noise, generated by the switching network, from getting into the source. It is typically made up of passive elements. A large body of the literature has been devoted to design, analyze, and package input and output filters for different power electronic systems by modeling, experimentation, and simulation. For example, the input filter of the power factor preregulator is used to perform line filtering and electromagnetic interference (EMI) filtering.
At least one investigation into the use of series-pass device (SPD) to filter out input current harmonics of switching converters has been performed (for example, see “W. Fan, K. K. Yuen and H. S. Chung, “Power Semiconductor Filter: Use of Series-Pass Device in Switching Converters for Filtering Input Current Harmonics” in IEEE Transactions on Power Electronics, vol. 31, no. 3, pp. 2053-2068, March 2016 [“Fan”]” [the entirety of which is herein incorporated by reference]). This idea is based on connecting a SPD in series with the input of the switching converter so that the input current of the entire system can be profiled by adjusting the biasing condition of the SPD. To minimize the power dissipation of the SPD, the input impedance of the switching converter is controlled to make the SPD operate at the boundary between the linear and saturation modes.
Accordingly, there is a need for providing a fast dynamic response to regulate the voltage across targeted electronic elements.
SUMMARYIn accordance with one aspect of the disclosure, a fast voltage stabilizer is described where under an arbitrary supply voltage variation, a fast dynamic response to regulate the voltage across a targeted electronic element can be provided no matter what the operating mode of the entire electrical circuit is, including but not limited by constant current mode, constant output resistant mode and constant power mode.
In accordance with another aspect of the disclosure, a fast voltage stabilizer wherein an actual voltage across a targeted electronic element is sensed is disclosed. The actual voltage is compared with a reference voltage. A control signal is generated, wherein in response to the control signal, an external current path is provided to maintain current flow and stabilize the actual voltage through charging or discharging an input capacitor and a supply filtering capacitor.
The foregoing aspects and other features various exemplary embodiments of the invention are explained in the following description, taken in connection with the accompanying drawings, wherein:
Current control circuit is widely used to control the flow of electric charge in electric networks. An ideal current source can maintain its current independent on the voltage across it and has an infinite output impedance across it. It is preferably implemented by connecting a voltage source connected in series with a linear-type series-pass device (SPD) because linear-type SPD generally provides fast dynamic response, small output ripple current, and low output noise. Such SPD is used to control the value of the output current of the voltage source. Nevertheless, in order to minimize its power dissipation, it is preferably to have low voltage drop across the SPD.
The present invention proposes a current regulation structure with a fast voltage stabilizer to minimize the voltage fluctuation on the SPD. As shown in
It should be noted that the voltage stabilizer allows bidirectional power flow and has fast response to regulate the voltage across the SPD under the variation of the supply voltage. In some applications, such as power factor correctors and DC-DC power supplies connecting with DC microgrid, the electric circuit connecting between the current regulator and the load is typically a power converter. If the power converter has bidirectional power flow control and fast dynamic response, the function of the fast voltage stabilizer can also be performed by the power converter.
According to one exemplary embodiment, the proposed structure is verified by applying it to control the input current waveform of a power factor corrector using a boost DC/DC converter. The circuit is shown in
Therefore, various exemplary embodiments of the invention are designed and placed into the PFC to replace the previous approach.
As shown in
While SPD is regulating the current flowing through itself according to the control signal vi,control, the voltage across the SPD vT is retrieved as an information for Controller M (26). Controller M (26) is treated as the control system of Fast Voltage Stabilizer as mentioned above. The function of M is to manipulate the operation of PCS so that the voltage across the input energy buffer of PCS is regulated to maintain a desired level of vT, that is, vT,ref.
In this implementation, a switching network is applied to realize the idea. According to
A. Boost Mode
The operation of this mode is similar to a boost converter operation and is briefly described below (where
The input current iin is sensed and processed with vi,ref to generate the signal vi,control to control the current flowing through SPD.
At the same time, vT is sensed and processed with vT,ref by the Controller M. Thus, it derives the gate signals for the switches S1 and S2. If vT>vT,ref, the duty cycle of S1 will decrease and that of S2 will increase, and vice versa. Typically, vT,ref is set at 1V to minimize the power loss of SPD, but not limited to any voltage level.
iin starts from zero in every half cycle of the mains voltage. If the PCS purely operates in boost mode, S1 is turned off by the Controller M to charge up Cin by iin and thus reduce vT. As discussed in Tung, the voltage across SPD, vT(t), is
The voltage across the SPM is maximum at tVT,Peak and the peak value is VT,Peak. It can be shown that
Thus, tVT,Peak and VT,Peak increase as Iin,Peak decreases. To reduce VT,Peak, Cin is charged up by the output capacitor with the converter operated as a buck converter. The operation is described below.
B. Buck Mode
Apart from maintaining the output voltage, the output capacitor is also used to charge up Cin, so that the input voltage vin follows the profile of vs. The average value of iL, īL,av, is
for ω t ϵ[0, π],
- where icin(t) is the current through Cin.
As shown in
Hence, this mode starts at t=0 and ends at t=tx.
Starting from the zero-crossing point, iin will increase and will thus accelerate charging of Cin when vo reduces, and then reverts to the boost mode.
Finally, as derived in Fan, the ideal efficiency of the system η is
where Vs,rms is the rms value of the rectified supply voltage vs.
Since the voltage across the SPD determines the energy efficiency, it is thus advantageous to use low-voltage devices, which have small channel length modulation effect, low leakage current, low voltage drop, and fast response.
Thus, low-voltage devices with low channel length modulation effect and low effective saturation voltage can be chosen for this high-voltage application. This confirms the function of the idea of exemplary embodiments of the invention is capable to remove high-voltage stress across SPD appears around the zero crossings. Take the previous work in Tung as an example, the flyback PFC prototype in Tung has a SPM in cascode structure constructed by connecting a high-voltage device in series with a low-voltage device. Experimental results show that the voltage stress on the SPM is higher than 100V (
According to various exemplary embodiments, the controller (or processor) 26 may comprise a microprocessor coupled to a memory, such as on a printed circuit board for example. The memory could include multiple memories including removable memory modules for example.
It should be understood that components of the invention can be operationally coupled or connected and that any number or combination of intervening elements can exist (including no intervening elements). The connections can be direct or indirect and additionally there can merely be a functional relationship between components.
It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.
Claims
1. An apparatus comprising:
- a controller; and
- at least one memory having stored therein machine-readable instructions;
- the at least one memory and the machine-readable code configured to, with the at least one controller, cause the apparatus to perform at least the following:
- sense an actual voltage;
- compare the actual voltage with a reference voltage; and
- generate a control signal, wherein in response to the control signal, an external current path is provided to maintain current flow and stabilize the actual voltage through charging or discharging an input capacitor and a supply filtering capacitor.
2. The apparatus of claim 1, wherein the actual voltage is a voltage across a targeted electronic element.
3. The apparatus of claim 1, wherein the actual voltage is a voltage across a series pass device (SPD).
4. The apparatus of claim 1 wherein the control signal is sent from the controller to a transistor.
5. The apparatus of claim 1 wherein the apparatus comprises a bidirectional linear-mode voltage stabilizer.
6. The apparatus of claim 1 wherein the control signal is sent from the controller to a bidirectional power converter.
7. The apparatus of claim 1 wherein the apparatus comprises a bidirectional switching-mode voltage stabilizer.
8. The apparatus of claim 1 wherein the apparatus comprises a voltage stabilizer, wherein the voltage stabilizer is configured to provide, under an arbitrary supply voltage variation, a dynamic response to regulate the voltage across a targeted electronic element regardless of the operating mode of the entire electrical circuit, including constant current mode, constant output resistant mode and constant power mode.
9. A method comprising:
- sensing an actual voltage;
- comparing the actual voltage with a reference voltage; and
- generating a control signal, wherein in response to the control signal, an external current path is provided to maintain current flow and stabilize the actual voltage through charging or discharging an input capacitor and a supply filtering capacitor.
10. The method of claim 9, wherein the actual voltage is a voltage across a targeted electronic element.
11. The method of claim 9, wherein the actual voltage is a voltage across a series pass device (SPD).
12. The method of claim 9, further comprising sending the control signal from a controller to a transistor of a bidirectional linear-mode voltage stabilizer.
13. The method of claim 12, wherein the bidirectional linear-mode voltage stabilizer is configured to provide, under an arbitrary supply voltage variation, a dynamic response to regulate the voltage across a targeted electronic element regardless of the operating mode of the entire electrical circuit, including constant current mode, constant output resistant mode and constant power mode.
14. The method of claim 9, further comprising sending the control signal from a controller to a bidirectional power converter of a bidirectional switching-mode voltage stabilizer.
15. The method of claim 14, wherein the bidirectional switching-mode voltage stabilizer is configured to provide, under an arbitrary supply voltage variation, a dynamic response to regulate the voltage across a targeted electronic element regardless of the operating mode of the entire electrical circuit, including constant current mode, constant output resistant mode and constant power mode.
16. A non-transitory computer-readable storage media storing computer-executable instructions, the instructions when executed on a processor cause the processor to:
- sense an actual voltage across a targeted electronic element or a series pass device (SPD);
- compare the actual voltage with a reference voltage; and
- generate a control signal, wherein in response to the control signal, an external current path is provided to maintain current flow and stabilize the actual voltage through charging or discharging an input capacitor and a supply filtering capacitor.
17. The non-transitory computer-readable storage media of claim 16, wherein the instructions when executed on the processor further cause the processor to send the control signal to a transistor of a bidirectional linear-mode voltage stabilizer.
18. The non-transitory computer-readable storage media of claim 17, wherein the bidirectional linear-mode voltage stabilizer is configured to provide, under an arbitrary supply voltage variation, a dynamic response to regulate the voltage across a targeted electronic element regardless of the operating mode of the entire electrical circuit, including constant current mode, constant output resistant mode and constant power mode.
19. The non-transitory computer-readable storage media of claim 16, wherein the instructions when executed on the processor further cause the processor to send the control signal to a bidirectional power converter of a bidirectional switching-mode voltage stabilizer.
20. The non-transitory computer-readable storage media of claim 19, wherein the bidirectional switching-mode voltage stabilizer is configured to provide, under an arbitrary supply voltage variation, a dynamic response to regulate the voltage across a targeted electronic element regardless of the operating mode of the entire electrical circuit, including constant current mode, constant output resistant mode and constant power mode.
Type: Application
Filed: Dec 6, 2019
Publication Date: Jun 10, 2021
Inventors: Ka Wai Ho (Diamond Hill), Chung Pui Tung (Kennedy Town), Po Wa Chow (Shatin), Wing To Fan (N.T.), Wan Tim Chan (Yuen Long), Ke Wei Wang (Tai Po), Shu Hung Henry Chung (Mid-levels), Chiu Sing Celement Tse (Yuen Long)
Application Number: 16/705,709